In recent years, a variety of projectors have been widely used in various video applications. For example, projectors can be used for making presentations, holding meetings or giving lectures in classrooms, boardrooms, conference rooms or home theaters. By the projector, an image signal from an image signal source can be enlarged and shown on a display screen. For reducing power consumption and overall volume, the illumination system of the current projector employs a solid-state light-emitting element (e.g. light emitting diode or laser diode) to replace the conventional high intensity discharge (HID) lamp.
Generally, the illumination system of the projector may emit three primary color lights, i.e. red light (R), green light (G) and blue light (B). Among the architecture of emitting red light, a solid-state light-emitting elements is commonly used to emit an excitation light to a wavelength conversion device (e.g. a phosphor color wheel) coated with a yellow phosphor agent, and the light is filtered through a filter to obtain the desired red light. However, in this architecture, the purity of the red light obtained is not good, and the conversion efficiency is not good.
In another commonly used architecture, a solid-state light-emitting element is used to emit an excitation light to a wavelength conversion device coated with a red phosphor agent, so as to emit red light, but the thermal stability of this architecture is poor. In addition, a solid-state light-emitting element can also be used to directly emit red laser light to obtain high-purity red light. However, the cost of manufacturing such architecture is expensive, and an additional cooling system is required, so the cost involved is high.
For overcoming the drawbacks of the conventional technologies, there is a need of providing an improved phosphor device.